1. Field of the Invention
This invention relates to devices for collecting cell samples from internal organs, and in particular to a catheter capable of simultaneously performing brush cytology and scrape biopsies of structures within biological ducts, employing a polymeric hook pad with relatively stiff irregularly shaped bristles for collecting cells from a sample site. More particularly, a wire guided catheter having a hook pad of a hook and pile fastener (e.g., Velcro) at its distal end is used for abrading against the duct walls to collect cells and tissue.
2. Description of the Prior Art
It is sometimes necessary to collect a sampling of cells from internal organs, typically using an endoscope or laparoscope to obtain access to the site to be sampled, for laboratory analysis in connection with a diagnosis. In connection with certain bodily ducts, a tumor in the tissue of the duct or in tissues adjacent the duct may present as a narrowing or stricture of the duct at a localized area. Cancer of the bile duct or the pancreatic ducts, for example, present as a narrowing or stricture. Similarly, strictures can be seen in the esophagus, the stomach, the colon, and other duct-like organs. It is useful in connection with diagnosis to examine the cells at a stricture to better assess its cause.
Known cytological techniques for collection of cell samples at duct strictures and other sites have a number of shortcomings. The diagnosis of pancreato-biliary malignancy is an example. Normally, an endoscope is used to obtain access to the collection site, for example the pancreatic duct leading from the pancreas to the duodenum. A cell collection tool that is basically an elongated brush usually having soft bristles set in twisted strands of wire is passed through the endoscope. Using the wire to pull the brush in opposite directions, the bristles are brushed over the inner wall of the duct at the stricture, in an effort to displace cells from the duct wall and capture the cells in the bristles. This technique is sometimes called "brush cytology" or just "cytology."
The brush can be placed in a sleeve to assist in guidance to the sample site, to avoid picking up cells from areas other than the stricture, and to protect the sample after it is collected. The sleeve can have one or more radio-opaque marks to help in placing the brush at the stricture. More particularly, fluoroscopy is used to visualize the location of the sleeve by the radio-opaque mark and therefore to assist in placing the brush in the stricture.
Unfortunately, brush cytology as described is only adequate to collect sufficient cells to effect diagnosis in about 18 to 70% of attempts. The technique offers no biopsy capability because it cannot effectively extract a gross tissue sample from the area of the stricture. Diagnosis of a potential malignancy, however, certainly requires dependable results in the collection of cells, and may require collection of a more extensive biopsy sample. To diagnose a malignancy associated with a stricture, for example, it may be appropriate to examine the mucous lining of the duct, the tissue of the duct wall and even adjacent tissues. The known brush cannot extract sufficient cells and tissue in a dependable manner. The known wire-carried brush can be reciprocated using the wire but it is not guided by the wire. Accordingly, the known brush is difficult to use effectively in difficult to reach, narrow areas of the ducts. Presently, a biopsy of the area of the stricture is obtained by passing a different instrument, typically a biopsy forceps, through the endoscope and then cutting away and removing a relatively large chunk of the tissue from the diseased area. However, use of biopsy forceps involves an inherent risk of perforating the duct, and for this reason their use is not preferred.